The present invention relates to a fastener for fixing laminated plate members.
A conventional fastener for fixing laminated plate members is shown in FIG. 12 and FIG. 13, which is disclosed in Japanese Utility Model Publication (KOKOKU) No. S58-60016.
A fastener 100 comprises a grommet 102 and a pin 104, which are formed of a flexible resin. The grommet 102 is inserted into mounting holes 110 and 112 of plate members 106 and 108, which are positioned and laminated, and the pin 104 is inserted into the grommet 102, so that the plate members 106 and 108 are fixed so as not to be separated from each other.
The grommet 102 includes a cylinder member 122 provided with a flange 120, and when the cylinder member 122 is inserted into the mounting holes 110 and 112, the flange 120 abuts against the upper plate member 106 to regulate the position of the grommet 102 in an inserting direction. On an inner peripheral surface of the cylinder member 122, four engagement claws 124 (three engagement claws 124 are shown in the figure) are formed near a mouth of the cylinder member 122 in a peripheral direction at equal intervals therebetween. Below each engagement claw 124 (a distal end side of the inserting direction), there is formed a slit 126 which is cut up to a distal end portion of the cylinder member 122, and accordingly, the distal end side of the cylinder body 122 is divided into four to form four elastic pieces 128 in a cantilever shape. Also, an inner peripheral surface side of each elastic piece 128 constitutes a protruding portion 130 that protrudes inwardly.
The pin 104 includes a pin main body 134 having a flange 132 at a head portion thereof. A male screw 136 is formed in a substantially entire area of a straight portion of an outer peripheral surface of the pin main body 134, and a distal end portion 138 has a tapered shape.
When the pin 104 is inserted into the grommet 102, the male screw 136 engages the claws 124, and receives an insertion load. When the pin 104 is further inserted as it is, the distal end portion 138 of the pin 104 pushes the protruding portions 130, and the elastic pieces 128 are expanded. Thereafter, the pin 104 is inserted until the flange 132 of the pin 104 abuts against a concave portion 140 formed on an upper surface of the flange 120 of the grommet 102, so that the elastic pieces 128 are expanded to the maximum and engaged with the mounting hole 112. This engagement condition is maintained by engagement between the male screw 136 and the engagement claws 124, and accordingly, the plate members 106 and 108 are clamped and fixed by the flange 120 and the elastic pieces 128.
In the conventional fastener 100 described above, however, since the male screw 136 is inserted while being always caught by the engagement claws 124 as the pin 104 is inserted into the grommet 102, a heavy insertion load is generated and maintained through the whole insertion process. This continuous insertion load causes poor workability and an additional burden to an operator.
The present invention has been made in view of the foregoing, and an object of the invention is to provide a fastener in which an insertion load is reduced and workability is improved.
Further objects and advantages of the invention will be apparent from the following description of the invention.